1. Field of the Invention
The present invention relates generally to printer ribbon tracking systems and more particularly to a ribbon tracking system for a thermal transfer printer which uses a plate for covering printer wiring under the ribbon frame which has a head portion gimbaled centrally on a small integral neck portion and adapted to deflect according to the movement of the ribbon.
2. Prior Art
Various attempts have been made in the past to provide effective means for correcting errors in ribbon tracking during printer operation. Most attempts, however, have either been implemented with limited success, or have been associated with high manufacturing costs, or both.
For example, U.S. Pat. No. 4,084,683 to Moss discloses a ribbon tracking system which includes guide means and roller means thereon which automatically tilts with the moving ribbon to correct errors in tracking of the ribbon. The system also includes a crowned pulley which is floatingly supported and journaled on a curved guide post with the pulley being axially moved along the guide post in a direction generally opposite the tracking error to correct the attitude of the moving ribbon. When a tracking error occurs due to an unbalance of forces acting on the ribbon and the centerline of the ribbon does not align with the radius of curvature of the guide post, the forces on the crowned pulley cause the pulley to center itself with respect to the moving ribbon. A ribbon tracking system of this kind is rather costly to manufacture, assemble and/or maintain due to its complex design.
Another example is commonly assigned U.S. Pat. No. 6,123,471 to Harb et al, which discloses a medium tracking bar mounted on a printer ribbon mechanism by way of La V-shaped metal flange which has a central aperture for receiving a compression spring-loaded screw. The screw and the compression spring function as a central pivot means for the medium tracking bar. The compression spring provides a force that resists pulling in and/or pushing away the medium tracking bar from a balanced central position. the resisting force is used to counteract the uneven stresses on a misaligned moving ribbon. This type of centrally pivoted and spring loaded medium tracking bar, although an improvement over the above-described Moss setup, involves a number of relatively costly components and requires a certain amount of assembly time which adds to the overall manufacturing cost of the system.
The present invention is directed to a ribbon tracking system for use in an image forming device having a printhead coupled to a ribbon frame comprising a plate including a first portion coupled to the ribbon frame downstream from the printhead and a second portion spaced apart from the first portion and adapted to contact a moving ribbon at a first edge. The plate also comprises a substantially small integral neck region between the first and second portions adapted to permit the second portion to deflect toward and/or away from the first portion to help equalize stress differentials between various portions of the moving ribbon to prevent wrinkling of the ribbon.
These and other aspects of the present invention will become apparent from a review of the accompanying drawings and the following detailed description of the preferred embodiments of the present invention.